What's a good way to make planks in a pattern from a vertices pattern (see image)
Select all the faces in Edit mode. Press I (letter not number) to inset, then press I again to inset all the individual faces. Only do a small inset so there's a small gap, then without deselecting the faces, press P and select > By Selection to separate your new faces into a new object.

From there you can extrude the faces up, and delete the object containing the filler that you no longer need.